Epigenetics is the study of how environment can influence genetic regulation. The realisation that foods can alter the genetics of an individual is interesting from a nutritional perspective because it explains the associations between certain nutrients and certain diseases. Contributions to disease previously thought to be related to genes, may actually therefore be related to the environment, that latter simply having an influence directly on the former. For example, the long chain fatty polyunsaturated acids eicosapentaenoic acid (EPA, C20:5 (n-3)) and docosahexaenoic acid (DHA, C22:6 (n-3)) are able to provide health benefits because they are responsible for regulating the synthesis of eicosanoid hormones that controlled cell function. In particular, both EPA and DHA may affect DNA methylation, a process that can regulate the expression of particular genes. An epigenetic role for omega-3 fatty acids may explain the inverse association between high intakes of omega-3 fatty acids and diseases such as cardiovascular disease.
The association between intakes of omega-3 fatty acids (including EPA and DHA) and DNA methylation patterns have been investigated. In one study researchers measured the DNA methylation of nearly 500,000 sites of DNA in 185 native Alaskans who have traditionally eaten high intakes of fish (about 20 times the US national average)1. The researchers identified 27 site on the DNA of the subjects that were associated with epigenetic regulation. The authors estimated that 78 % of significant associations were explained by the consumption of omega-3 polyunsaturated fatty acids. Therefore the methylation patterns in these subjects were associated with their intake of omega-3 polyunsaturated fatty acids. Further analysis showed that two of the identified methylation sites were associated with increase plasma glucose levels and increased low density lipoprotein levels, both risk factors for cardiovascular disease. Therefore omega-3 fatty acids may modify disease risk through methylation of DNA.
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